Re: [PATCH 16/35] writeback: increase min pause time on concurrent dirtiers

Peter Zijlstra
2010-12-14T18:56:19Z

On Tue, 2010-12-14 at 13:42 -0500, Valdis.Kletnieks@vt.edu wrote:
> On Tue, 14 Dec 2010 14:51:33 +0800, Wu Fengguang said:
>
> > > > + /* (N * 10ms) on 2^N concurrent tasks */
> > > > + t = (hi - lo) * (10 * HZ) / 1024;
> > >
> > > Either I need more caffeine, or the comment doesn't match the code
> > > if HZ != 1000?
> >
> > The "ms" in the comment may be confusing, but the pause time (t) is
> > measured in jiffies :) Hope the below patch helps.
>
> No, I meant that 10 * HZ evaluates to different numbers depending what
> the CONFIG_HZ parameter is set to - 100, 250, 1000, or some other
> custom value. Does this code behave correctly on a CONFIG_HZ=100 kernel?

10*HZ = 10 seconds
(10*HZ) / 1024 ~= 10 milliseconds